The invention relates to circuit board assemblies, and more particularly to mounting of double-sided printed circuit boards and the transfer of heat therefrom.
A byproduct of normal operation of an electronic circuit is thermal energy, i.e., heat, generated as the result of frictional effects of charge flow during operation of the electronic circuit. Greater charge flows, i.e., larger currents, generate more thermal energy. A build-up of thermal energy can, if not safely dissipated, cause undesirable operating characteristics in the electronic circuit and can even cause damage to the components of the electronic circuit and components of other nearby circuits. Heat build-up is of particular concern when space is limited, for example, in aircraft cockpits, under automobile dashboards and in other vehicle installations where space is a premium, also in portable and desktop computing and entertainment applications. In such applications, individual circuits are typically packed closely together and the opportunities to cool the circuits are limited.
One approach to dissipating this built-up heat while conserving space has been to mount two single-sided electronic circuit boards on opposing sides of a thermally conductive plate with the components facing outwardly away from the thermally conductive plate. The conductive plate is mounted in the electronics box using wedge locks. The heat generated electrically in the electronic circuits is carried by the thermally conductive mounting plate to the walls of the electronics box which is usually formed with fins on the exterior walls to dissipate the heat into the surrounding atmosphere. However, this approach is limited to less densely populated single-sided electronic circuit boards. Also, the electronic circuit boards with outwardly facing components are difficult to mate with other system components.
As noted above, modern electronics circuits are often installed in aircraft cockpits, under automobile dashboards, in other vehicle installations, and also in portable computing and entertainment applications. Electronics circuits used in these applications are subjected to damaging shock and vibration environments. Thus, another important consideration in the design and manufacture of electronic circuits and their mounting is to minimize susceptibility to applied shocks and vibrations. To that end, manufacturers of these devices typically strive to maximize the resonance amplification factor (Q) of the vibration system, as represented by the electronic circuit and its mounting.